(C) Different fractions of crude oil in petroleum industry
(III) Distillation at reduced pressure
(D) Chloroform-Aniline mixture
(IV) Steam distillation
Choose the correct answer from the options given below:
A.(A)-(IV), (B)-(III), (C)-(II), (D)-(I)
B.(A)-(I), (B)-(II), (C)-(III), (D)-(IV)
C.(A)-(III), (B)-(IV), (C)-(I), (D)-(II)
D.(A)-(II), (B)-(I), (C)-(IV), (D)-(III)
Solution & Explanation
### Core Logic
Evaluating standard NCERT laboratory purification matches:
- **(A) Aniline from aniline-water mixture:** Aniline is steam volatile and immiscible with water, so it is separated via **Steam distillation (IV)**.
- **(B) Glycerol from spent-lye in soap industry:** Glycerol decomposes at or below its boiling point, hence it is separated via **Distillation at reduced pressure (III)**.
- **(C) Different fractions of crude oil:** Separated using their small differences in boiling points via **Fractional distillation (II)**.
- **(D) Chloroform-Aniline mixture:** Separated due to a substantial boiling point difference via **Simple distillation (I)**.
### Pattern Recognition
Match key words directly: Glycerol/spent-lye always links to reduced pressure (vacuum distillation). Crude oil always couples to fractional columns. Aniline + water implies steam injection.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 11 Chemistry: Some Basic Principles of Organic Chemistry
Which of the following is the correct IUPAC name of given organic compound (X)?
The image shows structural representation of compound X with a double bond and a bromine substituent.
### Core Logic
To determine the IUPAC name of the compound shown in The image shows structural representation of compound X with a double bond and a bromine substituent.:
1. Identify the principal functional group, which is the double bond (alkene).
2. Find the longest carbon chain containing the double bond:
mathrmC1(H_2Br) - C2(CH_3) = C3(H) - C4(H_3)$$\mathrm{C1(H_2Br) - C2(CH_3) = C3(H) - C4(H_3)}$$
The longest chain has 4$4$ carbons, which means the parent alkane is butane, and with a double bond it's "but-2-ene".
3. Number the chain from the end that gives lower locants to the double bond. Starting from left or right both give the double bond at position 2$2$. However, starting from left gives substituent locants as 1$1$ (for bromo) and 2$2$ (for methyl), whereas starting from right gives substituent locants as 3$3$ and 4$4$.
4. Hence, correct numbering is:
- textC1$\text{C1}$: bonded to Bromine (-textBr$-\text{Br}$)
- textC2$\text{C2}$: bonded to Methyl (-textCH_3$-\text{CH}_3$)
- textC3$\text{C3}$: alkene carbon
- textC4$\text{C4}$: terminal methyl group
The image shows structural representation of compound X with a double bond and a bromine substituent.
Combining these rules, the name is: **1-Bromo-2-methylbut-2-ene**.
### Pattern Recognition
Double bond takes precedence over halogen substituent in numbering direction. If double bond is symmetrical (at position 2$2$ in a 4$4$-carbon chain), use the substituent positions to break the tie, choosing lowest possible locants (1$1$ and 2$2$ vs 3$3$ and 4$4$).
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 11 Chemistry: Organic Chemistry - Some Basic Principles and Techniques
Class 12 Chemistry: Haloalkanes and Haloarenes
An organic compound weighing 500mathrm\ mg$500\mathrm{\ mg}$, produced 220mathrm\ mg$220\mathrm{\ mg}$ of mathrmCO_2$\mathrm{CO}_2$ on complete combustion. The percentage composition of carbon in the compound is ______ %. (nearest integer)
(Given molar mass in mathrmg\ mol^-1$\mathrm{g\ mol}^{-1}$ of mathrmC: 12$\mathrm{C}: 12$, mathrmO: 16$\mathrm{O}: 16$)
Numerical Answer.Answer: 12 to 12
Solution
### Related Formula
\% mathrmC = frac1244 times fractextMass of mathrmCO_2 text producedtextMass of organic compound taken times 100$$\% \mathrm{C} = \frac{12}{44} \times \frac{\text{Mass of } \mathrm{CO}_2 \text{ produced}}{\text{Mass of organic compound taken}} \times 100$$
### Core Logic
Given:
- Mass of organic compound taken = 500 text mg = 500 times 10^-3 text g$= 500 \text{ mg} = 500 \times 10^{-3} \text{ g}$
- Mass of mathrmCO_2$\mathrm{CO}_2$ produced = 220 text mg = 220 times 10^-3 text g$= 220 \text{ mg} = 220 \times 10^{-3} \text{ g}$
Using the formula:
\% mathrmC = frac1244 times frac220 times 10^-3500 times 10^-3 times 100$$\% \mathrm{C} = \frac{12}{44} \times \frac{220 \times 10^{-3}}{500 \times 10^{-3}} \times 100$$\% mathrmC = frac1244 times frac220500 times 100$$\% \mathrm{C} = \frac{12}{44} \times \frac{220}{500} \times 100$$\% mathrmC = frac1244 times 44 = 12 \%$$\% \mathrm{C} = \frac{12}{44} \times 44 = 12 \%$$
Thus, the percentage of carbon is 12$12$.
### Pattern Recognition
Carbon dioxide has exactly 12/44 approx 27.27\%$12/44 \approx 27.27\%$ carbon by mass. Multiply the mass fraction of mathrmCO_2$\mathrm{CO}_2$ (220/500 = 0.44$220/500 = 0.44$) by 12/44$12/44$ to directly get 0.12$0.12$ or 12\%$12\%$.
### Evaluation Rubric / Model Answer
A perfect step-by-step conversion of organic compound mass and combustion carbon dioxide mass to obtain a precise 12$12$ percent carbon composition.
### Chapter Mix
Class 11 Chemistry: Organic Chemistry - Some Basic Principles and Techniques
Qjee_main_2025_08_april_eveningIUPAC Nomenclature
What is the correct IUPAC name of the following organic compound?
The molecule contains a five-membered carbon ring with one double bond, a hydroxyl substituent, and an ethyl group.
A. 4-Ethyl-1-hydroxycyclopent-2-ene
B. 1-Ethyl-3-hydroxycyclopent-2-ene
C. 1-Ethylcyclopent-2-en-3-ol
D. 4-Ethylcyclopent-2-en-1-ol
Solution
### Core Logic
Let us apply official IUPAC priority indexing rules:
1. **Principal Functional Group**: The hydroxyl group (-textOH$-\text{OH}$) possesses higher naming priority over double bonds and simple alkyl side chains. Thus, the carbon bearing the -textOH$-\text{OH}$ group is assigned position **C-1**.
2. **Numbering Direction**: We must number through the ring towards the double bond to assign it the lowest possible locant. Hence, the alkene carbons are given coordinates **C-2** and **C-3**.
3. **Locating Side Chains**: Proceeding with this direction puts the ethyl group at position **C-4**. The molecule contains a five-membered carbon ring with one double bond, a hydroxyl substituent, and an ethyl group.
Assembling the structural parts alphabetically:
* Substituent: `4-Ethyl`
* Parent root: `cyclopent-2-en`
* Suffix: `1-ol`
Combined IUPAC format: **4-Ethylcyclopent-2-en-1-ol**.
### Pattern Recognition
Principal suffix priority hierarchy: -textOH > textDouble bond > textAlkyl side-chain$-\text{OH} > \text{Double bond} > \text{Alkyl side-chain}$. Always fix the highest priority suffix at index 1 and head instantly towards the alkene bond to safely restrict locant numbers.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 11 Chemistry: Organic Chemistry - Some Basic Principles and Techniques
Q27jee_main_2025_08_april_eveningReactive Intermediates and Reagents
Match the LIST-I with LIST-II:
LIST-I
LIST-II
A. Carbocation
I. Species that can supply a pair of electrons.
B. C-Free radical
II. Species that can receive a pair of electrons.
C. Nucleophile
III. sp^2$sp^2$ hybridized carbon with empty p-orbital.
D. Electrophile
IV. sp^2/sp^3$sp^2/sp^3$ hybridized carbon with one unpaired electron.
Choose the correct answer from the options given below:
### Core Logic
Let us analyze each term carefully:
* **A. Carbocation**: Features a positively charged trivalent carbon atom. It represents an sp^2$sp^2$ hybridized carbon with an empty unhybridized p-orbital. Carbocation orbital hybridization diagram for Q27 - JEE Main 2025
* **B. Carbon Free Radical**: Contains a trivalent carbon carrying a single unpaired lone electron. It typically exhibits sp^2$sp^2$ or sp^3$sp^3$ hybridization depending on structural environments. Carbocation orbital hybridization diagram for Q27 - JEE Main 2025
* **C. Nucleophile**: An electron-rich chemical species containing a lone pair or negative charge capable of donating/supplying a pair of electrons.
* **D. Electrophile**: An electron-deficient chemical species possessing empty low-lying orbitals capable of accepting/receiving a pair of electrons.
### Step 1: Alignment Matrix
Matching each item yields:
* textA rightarrow textIII$\text{A} \rightarrow \text{III}$
* textB rightarrow textIV$\text{B} \rightarrow \text{IV}$
* textC rightarrow textI$\text{C} \rightarrow \text{I}$
* textD rightarrow textII$\text{D} \rightarrow \text{II}$
This sequence aligns flawlessly with Option (4).
### Pattern Recognition
Nucleophiles donate ('nucleo-loving' = seeks positive sites with its electrons), Electrophiles accept ('electro-loving' = seeks electron density). Carbocations explicitly harbor a vacant p-orbital because of their positive charge configuration, making identification extremely swift.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 11 Chemistry: Organic Chemistry - Some Basic Principles and Techniques
On complete combustion, 0.210 text g$0.210 \text{ g}$ of an organic compound containing C, H, and O yielded 0.127 text g$0.127 \text{ g}$ of textH_2textO$\text{H}_2\text{O}$ and 0.307 text g$0.307 \text{ g}$ of textCO_2$\text{CO}_2$. The mass percentages of hydrogen and oxygen in the given organic compound respectively are:
A. 53.41, 39.6
B. 6.72, 53.41
C. 7.55, 43.85
D. 6.72, 39.87
Solution
### Related Formula
Percentage of Hydrogen in organic analysis:
\%textH = frac218 times fractextMass of H_2OtextMass of Compound times 100$$\%\text{H} = \frac{2}{18} \times \frac{\text{Mass of } H_2O}{\text{Mass of Compound}} \times 100$$
Percentage of Carbon:
\%textC = frac1244 times fractextMass of CO_2textMass of Compound times 100$$\%\text{C} = \frac{12}{44} \times \frac{\text{Mass of } CO_2}{\text{Mass of Compound}} \times 100$$
Percentage of Oxygen:
\%textO = 100 - (\%textC + \%textH)$$\%\text{O} = 100 - (\%\text{C} + \%\text{H})$$
### Execution
Step 1: Compute the mass percent of Hydrogen:
\%textH = frac218 times frac0.1270.210 times 100 = frac0.2543.78 approx 6.72\%$$\%\text{H} = \frac{2}{18} \times \frac{0.127}{0.210} \times 100 = \frac{0.254}{3.78} \approx 6.72\%$$
Step 2: Compute the mass percent of Carbon:
\%textC = frac1244 times frac0.3070.210 times 100 = frac3.6849.24 approx 39.87\%$$\%\text{C} = \frac{12}{44} \times \frac{0.307}{0.210} \times 100 = \frac{3.684}{9.24} \approx 39.87\%$$
Step 3: Deduce the remaining mass percent of Oxygen:
\%textO = 100 - (39.87 + 6.72) = 100 - 46.59 = 53.41\%$$\%\text{O} = 100 - (39.87 + 6.72) = 100 - 46.59 = 53.41\%$$
Thus, the values of hydrogen and oxygen percentage are 6.72\%$6.72\%$ and 53.41\%$53.41\%$, matches with Option (2).
### Pattern Recognition
Always focus on the order requested by the question stem. The query specifies 'hydrogen and oxygen respectively'. Option 2 and Option 4 both show these numbers but reversed—verifying the targeted sequence protects your score line.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 11 Chemistry: Organic Chemistry - Some Basic Principles and Techniques
More Some Basic Principles of Organic Chemistry Questions — jee_main_2025_04_april_evening
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